The present invention relates to railway car trucks and, more particularly, to single axle railway car trucks.
The most common trucks for use with railway freight cars are four-wheel trucks wherein two axles, each connected to two wheels, are joined between laterally spaced side frames having a bolster extending therebetween. Such trucks are designed to support considerable loads with each car utilizing two separate four-wheel trucks.
When the railroad car is not required to support heavy loads, for example in carrying automotive trailers or single containers, then the load carrying capacity of the truck can be reduced substantially. One type of railroad truck designed to carry such reduced loads utilizes a single axle joining two wheels and supported from a single axle suspension system. The axle ends are supported in journal bearings which themselves act as supports for the railway freight car.
Two known single axle railway car trucks are shown in U.S. Pat. No. 4,445,439 and U.S. Pat. No. 4,561,360, both assigned to the assignee of the present invention. One problem with the swing hanger design truck shown in U.S. Pat. 4,445,439 is that the design is fairly complicated and, accordingly, expensive to produce. Another problem with known single axle railway trucks relates to the poor curving or lateral stability of such trucks when subjected to normal freight car speeds and track curving conditions. It is accordingly an object of the present invention to provide an improved single axle railway car truck having improved curving characteristics and lateral stability.